Manage episode 126340570 series 101472
Later we’ll also see how the ear can be fooled just as easily as the eyes with some “audio illusions.” So Pitch…Let’s start by looking at wikipedia, the source of all knowledge: “Pitch is a major auditory attribute of musical tones and is defined as an auditory perceptual property that allows the ordering of sounds on a frequency-related scale.” (Makes sense so far – although it’s a bit boring). “Pitches are compared as “higher” and “lower” in the sense associated with musical melodies. A pitch itself requires “sound whose frequency is clear and stable enough to be heard as not noise”. So essentially pitch is how high or low a note is. If we take middle C as our starting point PLAY CLIP Middle C then it’s pretty straightforward to identify when a note is much higher PLAY CLIP C High Octave or much lower PLAY CLIP C Low Octave Fine… that’s a basic definition sorted, so let’s start at the beginning. How do we decide what middle C actually sounds like? And how do musicians know what pitch to tune their instruments to?
PLAY CLIP A 440 We can safely label that as an A. A “hertz” is a unit of frequency – one cycle per second – that measures, in this case, the traveling wave or oscillation of pressure caused by vibrations that we discern as sound. So 440 hertz means 440 cycles per second. Sound is a traveling wave which is an oscillation of pressure – and humans perceive frequency of sound waves – as pitch. A 440 is called standard or concert pitch. It could just as easily be called C 523.3 (which is the frequency of C in hertz) but it just doesn’t have the same ring to it. In 1939 a conference actually had to be called in order to establish what we now call standard pitch, because up until then there had been no standardised tuning system. The conference agreed that we would use A440 as concert pitch and that’s what we use to this day. However, in reality there is still a divergence of tuning standards, and American orchestras particularly have a tendancy to tune slightly sharper to A 442 or A 444. Prior to 1939, there were no universally recognized pitch standards. It was possible to travel from one country in Europe to another or, in some cases, from one city to another and find the same music being played at completely different pitches. If we go back to the 1700s, to the Baroque period and the time of Bach, we can see just how much of a divergence there was. Musicologists who researched the Baroque period found several pitch levels which performances were given at, one of them being A 415. Because this is conveniently half a step (or one semitone) below our current tuning system, it was seized on as a convenient modern “baroque pitch” standard. As a result many “authentic performances” or “historically informed performances” or “period performances” or… you get the idea… use the much lower A 415 to tune to. The difference between the two pitches is notiecable. Here is A 440 PLAY CLIP A 440 and here is A 415 PLAY CLIP A 415 And just in case you can’t hear the difference, here are both played at the same time: PLAY CLIP A Both But were all performances of music in the 18th Century really at A 415? Of course not. In the Baroque Period, pitch levels as high as A-465 ( in 17th century Venice) and as low as A-392 (in 18th century France) are known to have existed. But how did we actually know that they existed? Did someone really leave an instrument lying around for 250 years – perfectly tuned? Well, actually that’s exactly what happened. And that instrument was the organ. Organs stay exactly in tune (minus a bit of wear and tear), and the tuning of those that were destroyed or became unplayable could easily be replicated – as the exact size, width and length of the pipes used in the original instruments was written down by the makers, and often repairers of the instruments as well. We know that tuning standards were very different and very diverse several hundered years ago purely based on the number of differently tuned organs – so many that composers even used to write pieces for specific instruments and specific churches. The organs were also tuned in such a way that certain scales and keys would sound “better” than others. This is because our modern “equal temperament” was not commonplace. In fact before the 20th Century there were numerous different tuning systems in operation. Tuning Systems Here is just a quick side note about tuning systems Today we use what is known as “equal temperament”. Equal temperament is something fundamental to our scale system, intonation, pitch and everything else – and as the name suggests, each note is spaced exactly apart so that we hear a scale like this: PLAY CLIP Equal Temperament However our equal temperament tuning system is not perfect. Third intervals are slightly flatter than they ought to be in order to allow for perfect 5th intervals which sound better and more pure. As a result we can modulate between keys with no noticable dissonances, but we lose the true “perfect” nature of – for example – playing in C major. This differs to Baroque keyboards which were tuned in such a way that certain “keys” sounded better than others on certain instruments. For example you might have a more perfect sounding performance of a piece in C major but when playing a piece in B major on the same instrument it would sound horrific. Other tuning systems have also been experimented with, and one notable example is Pythagorean tuning. This type of tuning is purely mathematical and has a different sound to the intervals that we are used to hearing: Here is a C major triad played in equal temperament: PLAY CLIP C Major Triad Plain And here is a C major triad played in Pythagorean tuning PLAY CLIP C Major Triad Pythagorean The difference is almost imperceptable, but the second chord contains a third (in this case an E natural) which is slightly raised and is closer to the “true” interval of a third. Bach’s well-tempered Klavier – 48 preludes and fuges, two for each of the major and minor keys, is the most famous compostional example of pieces written for all of the keys, and some see it as an 18th century call for standardised tuning. So that’s all our homework done, and now we have a good idea of how pitch is conventionally defined – but let’s see how it impacts on people’s lives and why pitch actually matters to us…One of the main reasons for knowing what role pitch plays in our daily lives is that it’s often used subliminally to convince us that something is new or progressive – a very effective marketing tool. When a song is reworked and covered, it’s often shifted up in pitch to make it sound more modern, exciting and different to the original. Let’s take the following example. Here is a clip of Journey’s famous “don’t stop believing”: PLAY CLIP Don’t Stop Believing Original Try and hold that in your mind. In 2009 the tv series “Glee” released their own, awful, cover version of the song, let’s take a listen. PLAY CLIP Don’t Stop Believing Glee Not only have they shifted the pitch upwards, but they have upped the tempo (or speed) to make their version sound more dynamic and modern.nThis is also the logic behind sudden key changes towards the end of pop songs. One such example is Dappy’s seminal “no regrets”, changing key in the last moments of the song to try and keep the interest going. PLAY CLIP Dappy’s No Regrets Key Change A true masterpiece. TV series pull a similar trick, often shifting their theme tune up for later series, to subliminally convince the audience that the show is moving forward: Listen to the theme tune taken from series 1 of Family Guy: PLAY CLIP Family Guy Original And now the theme tune taken from series 4 onwards. PLAY CLIP Family Guy Up
PLAY CLIP Family Guy Clash The scary thing is that we often don’t realise that this sort of thing happens, and it does happen – all the time. We need to be aware that it takes place, so that we can decide consciously whether we approve of the use of this technique or not, rather than accepting it subliminally. Pitch intervals are also used to convey meaning to us, the most well-known example being the sinister tritone. PLAY CLIP Tritone – sometimes known as the devil’s interval, the tritone is often used to remind us that we have left cash in the cash machine. PLAY CLIP Cash Machine At this stage we should spare a thought for the poor people who have the blessing and the curse that is known as Perfect Pitch. Perfect pitch is found in about 1 in 1000 people and is often defined as the ability of a person to name or reproduce a tone without external reference. Other terms such as “musical ear”, “absolute tone consciousness” or “positive pitch” are also used to refer to the ability. Essentially if you tell a person with perfect pitch to sing A 440 then they can. A listener with “perfect pitch” has an auditory system which appears to be no different from a regular listener. Instead “it reflects a particular ability to analyze frequency information, most likely involving high-level cortical processing.” Absolute pitch is an act of cognition, needing memory of the frequency and a label for the frequency (such as “B-flat” or D natural). Absolute pitch is more common among speakers of tonal languages such as Chinese or Vietnamese, languages which depend heavily on pitch variation across single words for lexical meaning. For example, Mandarin has four possible pitch variations, Cantonese – six.mPerfect pitch can be helpful in unusual ways, for example learning to drive.There have been several reported cases of teenagers with perfect pitch learning to drive by using the pitch of the engine revs to learn when to change gear, rather than observing the rev counter. PLAY CLIP Engine Noise Engines can make a discernable pitch just as any instrument can – as these clips proves: PLAY CLIP Happy Birthday Anthem Engine Not the most beautiful renditions but certainly passable, and so learning to drive via this method is perfectly legitimate, at least until we’re all driving round electric cars. But perfect pitch has its downsides. Let’s go back to the beginning of the programme with the Lacrimosa of Mozart’s Requiem. PLAY CLIP Mozart’s Requiem
Mozart’s Requem Clash Horrible. But should we perform music at Baroque pitch at all? Should we impose A 440 on others? What pitch would Mozart have performed his compositions at? Is it even desirable to perform music in a ‘historically accurate or informed’ way or do we have to accept that performances have to move forward to survive? Do we even want to replicate initial performance conditions? Is it even possible? Many of these questions don’t have answers and I supposed ultimately it comes down to personal preference. My goal is simply to make you think about it. Let’s now take a look at how musicians internalise and appreciate music with the much more common ability to perceive what is called “relative pitch”. Relative Pitch is somewhat different to perfect pitch and is a learned appreciation of the relative intervals of notes based on an existing or received tonal centre. Those with relative pitch can understand the interval between two notes and how they relate to one another if, for example, they are given A 440 as a reference point. The problem is that if someone gives you your starting note and lies to you, you have no idea that you are technically singing or playing out of tune. The ear can be deceived, and it can be deceived just as easily as the eyes. Like an optical illusion which tricks the mind there are several notable audio illusions which are absolutely fascinating. The first illusion is known as the “constantly rising tone” illusion: PLAY CLIP Rising Tone This is known as a Shepard tone, named after Roger Shepard, and consists of a sound with a superposition of sine waves separated by octaves. When played with the base pitch of the tone moving upward or downward, it’s referred to as the Shepard scale. If the same clip is played in sequence it seems as though the pitch is constantly rising: Here is the clip played 4 times in a row: PLAY CLIP x4 It sounds never ending. Here is the clip again 4 times – now with a gap between the iterations just to prove that I’m not making it up: PLAY CLIP x4 with gap The way the illusion works is that notes are layered in octaves. The ear is happy to accept the transition from one to the other and believes that the scale is constantly rising. The Shapard-Risset glissando uses a similar idea to create what appears to be a constantly descending slide, layering scales over each other. Take a listen. PLAY CLIP Glissando The overlaps are slightly more obvious but it isn’t entirely clear when the clip begins to repeat. And now to my personal favourite – the bottle which never fills up PLAY CLIP Bottle Fill Believe it or not we actually end up where we start off. This is another extension of the previous idea and uses a constantly repeating clip to fool the ear into hearing a never ending sequence. Our ears can deceive us in a number of ways and it’s a well-known fact that performers, particularly soloists, tend to play sharp when nervous due to hairs in their ears being affected by a quickening of the pulse, which causes their perception of pitch to alter. To them they are playing perfectly in tune but to the audience they seem slightly on the sharp side.So our ears can be just as easily deceived as our eyes, we just need to make sure that we are aware that it can happen. At this stage it is also worth pointing out the limits of the human ear. PLAY CLIP High Pitched Frequency Mosquito When we are children, our ears can hear between 20 and 20,000 Hz.The upper limit of our perception gradually decreases over time so that the average adult human hears between 20 and 16,000 Hz. Whilst giving you these stastistics I’ve been playing a high pitch frequency – well over 10000hz. If you were scrambling to turn off the radio then fear not, it will stop in a few seconds. If you can’t hear it then it is very likely that your hearing has depreciated by at least 10% since you were born. Here is the sound again, this time on it’s own, can you hear it? PLAY CLIP High Pitched Frequency This frequency is sometimes used as a ringtone by teenagers as normally it can only heard by under 20 year olds, meaning that they can leave their phones on in class at school. Synysthesia: Another fascinating area of pitch perception is a condition known as Synysthesia. Those who have the condition can effectively ‘see’ colour, and can relate certain pitches to specific colours. Most don’t agree what colour each note should be, but here is an example of one person’s colour associations: PLAY CLIP C White PLAY CLIP D Blue
With this individual, the sharper the note gets the lighter the colour, for example D# is light blue compared to D flat which is a darker blue. Not much is known about this condition but the association of colour to musical pitch is absolutely incredible. Pitch pervades our every day lives and if we make a conscious effort to be more aware of its importance and tried just bit harder to perfect the art of listening, then we’d be able to appreciate our surroundings that little bit more. Let’s not be oblivious to the usage of pitch. Let’s take some time to stop and listen. This documentary was produced and presented by Chris Berrow. For more information about any of the issues discussed in this programme, head to facebook.com/chrisberrow or follow @djchrisberrow on twitter.